The invention herein described relates generally to aircraft landing gear and, more particularly, to aircraft landing gear with an integrated brake actuation system.
Aircraft brake assemblies have traditionally been comprised of three major functional components, a torque tube, an actuator assembly and a heat sink (brake disk stack). These components are assembled into a brake assembly, which is known as a Line Replaceable Unit (LRU). An LRU is removed and replaced on a flight line as a single component. Accordingly, if one of the major functional components requires repair or replacement, removal of the entire LRU is effected for transfer of the LRU to a specialty shop for disassembly, repair and acceptance testing. This is an inefficient use of resources when one of the components requires more frequent servicing than the other components.
The present invention provides a different aircraft brake assembly, wherein the actuator portion of the brake assembly is no longer provided as part of the brake assembly but instead as part of the aircraft landing gear. Accordingly, the actuator portion or individual actuators assemblies are designated as LRUs, which are replaceable independently of other brake components, e.g., the torque tube and heat sink, which then comprise the brake assembly designated as a separate LRU. This new arrangement is particularly suited to electro-mechanically actuated brakes, where actuator maintenance intervals will typically be more closely related to landing gear maintenance intervals than to brake maintenance (i.e., hydraulic actuator and/or heat sink maintenance).
Accordingly, the invention provides a wheel and brake assembly comprising a wheel support, a wheel rotatably mounted on the wheel support, a torque transfer member coupled to the wheel support for transfer of torque from the brake disk stack to the wheel support during braking, a brake disk stack supported on the torque tube, and an actuator assembly mounted on the wheel support for applying braking force to said brake disk stack, wherein the brake disk stack and torque transfer member are removable from the wheel support without removal of the actuator assembly.
In a preferred embodiment, the brake disk stack is carried on the torque transfer member and removable therewith as a unit from the wheel support. The actuator includes a plurality of actuator modules individually removably mounted to the wheel support. The wheel support has at least one flange thereon to which the actuator modules are mounted, and the actuator modules have at least one mounting flange secured to an outboard side of the at least one flange. More generally, the actuator modules have one or more mounting flanges abutting axially outwardly facing mounting surfaces on the wheel support. The torque transfer member may be a torque tube having a mounting ring, and the mounting ring may be retained on the wheel support by a retainer and a thrust bearing interposed between the retainer and the rhounting ring.
In an embodiment of the invention, the torque transfer member may be relatively rotatable on the wheel support, and the torque transfer member and wheel support may include a cooperating lug and recess interengaged to transfer torque for the torque transfer member to the wheel support. A load transducer may be interposed between the lug and recess for sensing the transferred braking load.
According to another aspect of the invention, a wheel and brake assembly comprises a wheel support, a wheel rotatably mounted on the wheel support, a torque transfer member coupled to the wheel support for transfer of torque from the brake disk stack to the wheel support during braking, a brake disk stack supported on the torque tube, and an actuator assembly mounted on the wheel support for applying braking force to the brake disk stack, wherein the actuator includes a plurality of actuator modules individually removably mounted to the wheel support, and the actuator modules have at least one mounting flange abutting axially outwardly facing mounting surface on the wheel support.
In a preferred embodiment, each actuator module includes a housing, a reciprocating ram mounted in the housing, an electric motor, and rotary-to-linear motion transfer device connecting the motor to the ram, and wherein the reactionary axial loads caused by the motion transfer device are passed as compression loads from the motion transfer device to the mounting flange.
The foregoing and other features of the invention are hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail one or more illustrative embodiments of the invention, such being indicative, however, of but one or a few of the various ways in which the principles of the invention may be employed.